Seriously About Pronation and Kick Serve #1

Discussion in 'Tennis Tips/Instruction' started by toly, Dec 24, 2010.

  1. LeeD

    LeeD Bionic Poster

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    How can court surface affect service speeds?
    Are you kidding me?
    On a fast slick grass court, everyone TRIES to serve fast, both serves.
    On the roughest, slowest, tackiest, wettest clay court, you might hit some flat fast ones once in a while, but you know they won't be very effective, and no reason to risk your second serve by pushing into the 100's, so you slow that serve way down.
    You gotta know that, if you play tennis.
     
  2. toly

    toly Hall of Fame

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    But, David Ferrer is doing that even after impact. See picture above please. Is it OK?
     
  3. Ajtat411

    Ajtat411 Semi-Pro

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    ^Well, yeah, but as long as it's not too early before impact, otherwise you will be "muscleing" the ball as people call it.

    You can do anything you want after you hit the ball but most likely the ball will come back, so the earlier you can recover/relax then the more time you have for the next shot.

    From impact to follow thru is a pretty short time. He doesn't hold that tension while he's recovering back to the middle. :)
     
  4. toly

    toly Hall of Fame

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    I’ve never played on clay. You got good point. Thank you very much!
     
  5. toly

    toly Hall of Fame

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    What about the wrist whip effect and how hard we should grip racquet’s handle before and during impact?:)
     
  6. Ajtat411

    Ajtat411 Semi-Pro

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    You tell me about the wrist whip effect, sounds like you know more than me.
    I'm always up for learning new stuff. :)
     
  7. gzhpcu

    gzhpcu Professional

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    The surface affects the service strategy. What kind of serve you use. The surface physically changes the bounce characteristics.
     
  8. gzhpcu

    gzhpcu Professional

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    On the serve your arm must be "loose like spaghetti". Grip is loose to allow the wrist to be elastic. Some top players even keep the pinky off the racket. On the serve you grip mostly with the thumb and forefinger, the bottom three are kept very loose so as not to freeze up your wrist.
     
  9. gzhpcu

    gzhpcu Professional

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    The grip on the racket is fairly loose prior to impact, this allows a backwards extension of the wrist, a lagging of the racket head, creating a stretch-shorten cycle acceleration of wrist and forearm to create the whipping effect. Hips turn ahead of the arm. See Federer.
     
  10. toly

    toly Hall of Fame

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    About Whip physics, see http://tt.tennis-warehouse.com/showthread.php?t=345688&highlight=toly please. I’m not very big fan of that theory in case of tennis strokes.
    According to Bruce Lee’s philosophy, how hard we should grip handle before and during impact phase of the serve and FH?
     
    Last edited: Dec 31, 2010
  11. gzhpcu

    gzhpcu Professional

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    Plagenhoef, one of the pioneers of tennis analysis, in his classic "The fundamentals of tennis", studied films of the serves of the top players of the sixties, and saw that certain swings, even though slower, resulted in a faster serve because of a tighter grip at the moment of impact. He maintained that the striking mass varied with the firmness of the grip at impact.
     
  12. Ajtat411

    Ajtat411 Semi-Pro

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    I think I understand why the wrist is whipped at the end but haven't really looked into the theory of it.

    I'm not a practicing martial artist but am a fan of Bruce Lee and his free flowing philosophy. I think it can be related to tennis in some way but am not the best at explaining it. Though I have a feeling that it all ties together.:)
     
  13. LeeD

    LeeD Bionic Poster

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    That whip physics thing....
    Applicable to flat shots.
    Not at all applicable to heavily sliced or topped shots.
     
  14. toly

    toly Hall of Fame

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    Loose arm?

    Thanks gzhpcu. This is very interesting data. I really lost ground about this loose arm (spaghetti) idea.
     
  15. LeeD

    LeeD Bionic Poster

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    Spaghetti right to the moment of impact, then consider a slightly firmer grip.
    You know how a head heavier racket can (might) serve first flats harder than a head lighter racket? Mass does affect ball rebound.
    Kinda like the idea that a baseball player, one big and strong, wielding a HEAVY bat, can hit the ball farther than a tiny tyke who swings just as fast, but uses a lighter bat.
     
  16. stecken71

    stecken71 New User

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    Anatoly, I just want to thank you for the diagram and the ideas you mentioned. It does take a little conceptualizing and deep thinking to understand everything. I kept thinking about that 45-90 degrees and tried that Taylor Dent grip further down the handle. I've never hit as hard as I did tonight during my serve practice on everything: flat, slice, top, kick, American twist. I'm not going to debate here with everyone, because I never do. But I know for myself, your ideas are completely correct as to how to get more pronation.
     
  17. charliefedererer

    charliefedererer Legend

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    Toly,

    You may be interested in these two videos by Jim McLennan of Tennisone.com. He uses different terminology than you, but advocates exactly what you have shown about having a much more forceful pronation (and serve) by maintaining the Beta angle at about 35 degrees:

    Racquet Angle on Serve http://www.youtube.com/watch?v=1t6bLABbebc&feature=related

    Serving Leverage http://www.youtube.com/watch?v=7bsYFra60Q0&feature=related

    When I first saw these videos several years ago, they made a lot of sense. I consciously tried to change what you describe as the "beta angle" and immediately got more "pop" on my serve.
     
  18. LeeD

    LeeD Bionic Poster

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    Well, certainly makes sense, how can you pronate with any added speed if your racket is aligned with your forearm?
    McEnroe might argue, but his serve, being great with the wide slice, is not nearly fast compared to every other player of his era.
    High strikepoint is all nice and cozy, but being able to hit a fast ball with heavy pronation is more important.
     
  19. toly

    toly Hall of Fame

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    Thanks for your understanding and support. See you on US Open 2011 or Olympics 2012.:)
     
  20. toly

    toly Hall of Fame

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    This is Jim McLennan from tennisone.com. I saw these videos many times. But, thank you anyway. He preaches the same idea (arm pronation) as I do. But, I don’t like his explanations.
    He says, "If we have racquet off line with forehand we can increase the leverage and force".
    It could be true, if we were able to apply our left arm to racket tip, then we would increase leverage and torque. Unfortunately, we cannot do that. But, we can increase radius RH = 25''sin(β)
    by increasing beta angle.
     
    Last edited: Dec 13, 2011
  21. toly

    toly Hall of Fame

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    What happened to you LeeD? Incredibly, you begin praising pronation!
     
    Last edited: Dec 13, 2011
  22. stormholloway

    stormholloway Legend

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    This is what I'm trying to work on at the moment. I get that the kick serve is like a "throw" across the ball and to the side rather than a "throw" into the court, but I just can't seem to time pronation properly.
     
  23. charliefedererer

    charliefedererer Legend

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    I don't like the term "leverage" that Jim McLennan uses here, and Pat Dogherty (the Bollitieri "Serve Doctor") uses in his videos. "Pronation" seems like a better overall description of the motion taking place (even though it is a combination of pronation at the foream and internal rotation at the shoulder.)

    But it was Systemic Anomaly that pointed out that the term "lever" is technically correct if you consider the action at the elbow as a third class lever, with the force between the fulcrum [at the elbow] and the distal load [the racquet]. [​IMG]
    "Your arm (fig. 1-6) is a third-class lever. It is this lever action that makes it possible for you to flex your arms so quickly. Your elbow is the fulcrum. Your biceps muscle, which ties onto your forearm about an inch below the elbow, applies the effort; your hand is the resistance, located about 18 inches from the fulcrum. In the split second it takes your biceps muscle to contract an inch, your hand has moved through an 18-inch arc. You know from experience that it takes a big pull at E to overcome a relatively small resistance at R. Just to experience this principle, try closing a door by pushing on it about 3 or 4 inches from the hinges (fulcrum). The moral is, you don’t use third-class levers to do heavy jobs; you use them to gain speed."
    - http://www.tpub.com/content/engine/14037/css/14037_13.htm
    (Of course during the serve, it is the triceps extension at the elbow that is the third class lever action.)

    So perhaps the use of the term "leverage" actually does explain the principle force/speed generated in the arm during the serve. The last bit of pronation at the end merely redirects the vector of the force.
     
    Last edited: Jan 10, 2011
  24. toly

    toly Hall of Fame

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    Why pros spread their fingers (Roddick pistol grip)?

    The arm pronation rotates the racquet in horizontal plane; hence the gravity is not important. In this case we cannot use directly first-class lever etc model. But, to simplify the matter, let assume the racquet’s inertia behave like gravity force (load). Figure 1 and figure 2 demonstrate the hand’s functions, while pronation beta angle is 90°.
    [​IMG]
    Figure 1
    The part of the hand around index finger creates force F1. The pinky could be some kind of fulcrum. It would be like third-class lever. The force F1 generates torque T = F1*D, where D is the size of hand , see fig. 1. To increase D, and thus torque, a lot of tennis players spread their fingers.


    Moreover, the hand around pinky is also able to exert force F2, see figure 2.
    [​IMG]
    Figure 2
    The index finger would be fulcrum. The hand works like first-class lever and creates torque T2 = F2*D. Torques T1 and T2 would rotate the racquet in horizontal plane.
    If pronation beta angle equal zero, the hand can treat the racquet handle as well as the handle of the screwdriver only. The racquet handle diameter (d) is usually much less than the size of the hand with spread fingers (D). And hence, the hand produces much less torque than in case as beta = 90°.
    if the beta angle is any value between 0° and 90°, then the torque can be calculated according to formula T =F((D-d)sin(β) +d).
     
    Last edited: Feb 29, 2012
  25. charliefedererer

    charliefedererer Legend

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    ^^^I'm not sure why you chose to emphasize the the lever action at the wrist in your most recent post.

    While salsinglesa makes an important point in his last point in a concurrent thread on levers ( http://tt.tennis-warehouse.com/showthread.php?t=361952 ) I thought from the illustration provided that the most obvious lever in the serve concerning pronation was at the elbow, with the foream, hand and racquet essentially acting as a unit distal to the fulcrum at the elbow.

    The somewhat less obvious, but very important lever for "pronation" (anatomically correct term of internal rotation) is at the shoulder.

    The wrist does go from extended to neutral, and there is ulnar deviation, but the "wrist action" contributes relatively little to the force of pronating and hitting the ball.

    But yes, action of multiple levers at the wrist, elbow, shoulder, spine, hips, knees and ankles all contribute to the multiple stage catapult making up the kinetic chain.
     

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